The present invention relates generally to bottle caps which form closures on containers which are used in liquid dispensing systems.
Water coolers which use bottled water, such as the system shown in U.S. Pat. No. 5,121,778 (the "'778 patent"), are generally equipped with reservoirs. The reservoirs are kept filled with water supplied by an inverted large capacity water bottle. The capacity of such water bottles is generally five to six gallons.
In recent years, water cooler manufacturers have addressed problems with traditional water cooler systems. Those problems include the difficulty of inverting an open water bottle, and concerns relating to the growth of bacteria in the reservoirs resulting from exposure of the reservoir to the atmosphere. Examples of attempts to solve these problems are shown in the '778 patent, as well as in U.S. Pat. No. 4,699,188 (the "'188 patent"). In the '188 patent, a probe capable of piercing a cap on the water bottle is rigidly connected to the base of the support for the water bottle. The bottle cap includes a central tube with a pierceable membrane at one end of the tube. The tube is integrally formed with the bottle cap. Earlier attempts to solve problems associated with inverting a filled water bottle are shown in U.S. Pat. Nos. 4,846,236 and 4,597,423.
The system shown in the '778 patent includes a blunt probe which displaces a frangible plug integrally formed at one end of a central tube in the water bottle cap. The blunt probe of the '778 patent is equipped with means for pulling the frangible plug back into engagement with the central tube in the event that the bottle is lifted from the probe. This provides clear advantages as compared to systems in which a water bottle cap is completely removed prior to being inverted and placed on a water cooler. First, the problem of spilling water, when the bottle is initially installed, is solved, since the frangible connection remains intact and the cap remains sealed until a seal between the probe and the central tube has been achieved. Second, the plug seals the central tube automatically upon removal of the bottle from the cooler, even if the bottle is not empty. This eliminates spillage if it becomes necessary to remove the bottle from the cooler before the bottle is empty. Such removal may be necessary, for example, if repair or relocation of the cooler is required.
Finally, the resealing of the cap by the plug upon removal of an empty bottle provides protection against contamination of the empty bottle on its return trip to a water bottling facility. The inability to remove and replace the plug without the use of a probe provides the cap with a form of tamper evidency upon which bottlers can rely when deciding what kind of cleaning process to use in preparing a bottle for refilling.
However, the cap shown in the '778 patent has at least two inherent problems. First, there is a tendency for the edges of the central tube of the '778 cap to pry the plug away from its engagement with the blunt probe. When this happens, the plug does not engage the central tube and the water bottle is not sealed. This absence of a seal will result in spillage if the bottle is removed before it is empty, and in the loss of contamination protection for its return trip to the water bottling facility.
Another problem associated with the cap shown in the '778 patent is the difficulty of molding or constructing the cap as it is shown in the '778 patent. The cap has a combination of undercuts which make it impossible to mold the cap in one entire piece. Unless the cap is assembled from two pieces, such as those shown in FIG. 8 of the '778 patent, a situation known as "trapped steel" will occur, which prevents the cap from being removed from a mold without destroying the cap. The presence of the multiple undercuts and the criticality of molding the frangible connection between the plug and the central tube in the cap requires that the cap of the '778 patent be initially formed of two components. Those components must subsequently be welded or otherwise bonded together to form a single unitary cap. The welding or bonding operation is somewhat problematic in that the connection between the two components must not only be structurally sound, but must form a seal. In addition, the heat generated by a sonic-welding operation may detrimentally affect the frangible connection by lowering the breaking point of that connection. Maintaining a predictable and consistent breaking point for the frangible connection is required to ensure that the blunt probe fully engages the plug prior to breaking of the frangible connection.
A further problem associated with manufacture of the cap shown in the '778 patent relates to the handling of the component which contains the frangible connection. In order to weld the two components which comprise the cap, the portion containing the central tube and the plug frangibly connected thereto must be fed or otherwise conveyed to a position in which it can be welded to the remaining part of the cap. Handling operations must be done carefully so as not to prematurely break or weaken the frangible connection. If the frangible connection is weakened or otherwise improperly formed, the plug may have a tendency to leak or prematurely break free from the central tube of the cap before a secure connection between the plug and the probe has been achieved. When this occurs, the plug will come floating to the surface of the water in the bottle. This is a highly undesirable condition referred to as creating a "floater". The surface of the water is a highly visible location in most cooler/bottle arrangements, and users of the system do not like to see pieces of plastic floating in the water they are about to drink. Creating a "floater" also has the earlier discussed disadvantages of spillage upon early removal of the bottle, and the lack of a seal for the bottle's return trip to the bottling facility.
The above described problems and disadvantages are overcome by a cap for bottles used in water cooler systems which includes a main outer cap and an inner cap. The inner cap forms a seal on the outside surface of a central tube carried by the outer cap. Further, by causing the inner cap to seal against the outside surface of the central tube, the tendency for the inner cap to prematurely disengage from the probe is greatly reduced.
A cap of the present invention is comprised of two parts. The first part is an outer, or main, cap body, and is comprised of a generally cylindrical skirt and a central tube joined to and integrally formed with the skirt by an annular base. The central tube is equipped with external retaining means in the form of a circumferential bead formed on the outer surface of the central tube. The second part of the cap is an inner cap which is comprised of two generally cylindrical concentric sleeves, a guide sleeve and a sealing sleeve, joined by an inner cap base. The guide sleeve is smaller in diameter but longer in axial length than the sealing sleeve. The sealing sleeve has retaining means in the form of a circumferential bead formed on its inside surface. The bead on the sealing sleeve cooperates with the external bead on the central tube of the first component of the cap. The guide sleeve has a tapered free end which facilitates insertion of the guide sleeve into the central tube. The guide sleeve ensures proper concentric alignment of the sealing sleeve with respect to the central tube, thus enhancing the reliability associated with resealing of the central tube when the bottle is removed from the cooler. Splines or axial channels are formed on the outside surface of the guide sleeve to prevent buildup of pressure in the space between the two sleeves as the cap is placed into engagement with the central tube. The inside edge of the free end of the guide sleeve is equipped with means for engaging and being retained by a blunt probe having a retaining groove formed thereon. The annular base of the main cap is provided with a recess into which is placed a removable protective label which prevents the inside of the guide sleeve and the inside of the central tube from becoming dirty during shipment of bottles equipped with caps of the present invention.
These and other features and advantages of the invention will be better understood upon a reading of the following detailed description of the invention read in conjunction with the accompanying drawings, wherein: